The present invention relates in general to data processing systems, and in particular, to data transmission over an Audio Encoder/Decoder (AC)-97 protocol data link using both AC-97 protocol and non-AC-97 protocol devices.
In considerations during computer system design, it is becoming increasingly common in all market segments of the home and business PC industry to use both Register Jack (RJ)11 telephone line and standard RJ45 connection schemes for data and Ethernet transmissions. Another major consideration in the design of Personal Computer (PC) systems is resource consumption. With more items being added to increase the usability and connectivity of the PC, available resources (I/O addresses, interrupt request/knowledge, Direct Memory Access (DMA) channels, etc.) within the PC are harder to find.
PC manufacturers are always looking for ways to lower the cost of computers they sell. Host signal processing is one of the cost saving measures which is being extensively used. As processor speed increases, tasks that used to be handled in separate (and expensive) stand alone devices, are being done by the main system processor. Simple, low-cost interface devices are used for Input/Output (I/O), Analog to Digital (AD) and Digital to Analog (DA) functions. Integrating functions into the main processor lowers overall system cost, but processing of these functions still requires system resources.
To deal with the problems that arise when functions are integrated, manufacturers have developed interface data communications standards. One standard has emerged which many manufacturers use to address some of these design issues. The AC-97/Audio Modem Riser (AMR) specification, authored by Intel, allows multiple audio and modem devices to be present in a system while using only one set of system resources. The AC-97/AMR standard employs a Time Division Multiplexing (TDM) scheme with a stated maximum data rate well below that needed even for one megabit Ethernet traffic. Communication using the AC-97 specification supports the use of multiple data streams, so it is possible to have a sound card device and a xe2x80x9cv.90xe2x80x9d (standard for communicating 56 Kbps upstream and 32.6 Kbps downstream) modem operating at the same time. If a separate data connection is present (e.g., Home Phoneline Network Alliance (HPNA), G. Lite, or a standard 10BaseT interface), communication using these protocols may operate together within the functionality of the AC-97 specification. Multiple data streams, operating concurrently, are considered a xe2x80x9cnormalxe2x80x9d functionality in AC-97 so any attempt at a new communication solution within AC-97 must allow at least the same level of simultaneous operation.
Presently many PC/motherboard manufacturers are offering some of (if not all) the AC-97 features integrated onto the system motherboard. The AC-97/AMR link is defined as a motherboard resource in the Intel AC-97 specification and not a user/field connection. This allows the motherboard designers complete control of resource assignments and allows multiple feature levels, depending on the performance and price targets of the design. Since AC-97 and the AMR connector are motherboard resources, non-standard functions may be implemented without any additional customer or field support problems. Additional customer or field support problems may be reduced because once the PC is in the field, the functions of the devices are transparent to the user. The drivers are included in the operating system by the Other Equipment Manufacturer (OEM), so no additional support is required. A more traditional approach for modifying or changing communication functionality, where the user adds modems and network cards, creates a lot of support issues directly related to resource allocation and conflicts. Some OEMs indicate that add on modems and network cards are responsible for more than fifty percent of the technical support calls taken every year. As the preceding illustrates, resource shortages, software device driver conflicts, and high system cost are all challenges facing today""s PC and motherboard designers.
The AMR connector using the AC-97 protocol is becoming more common. The AMR connector is used primarily as a modem port, giving the system a simple digital interface for a xe2x80x9cv.90xe2x80x9d implementation. All the signal processing is done on the host processor and the sensitive analog components reside on an add-in AMR card. The sound card functions are increasingly done on the motherboard, so that it may not be necessary for the AC-97 link to carry sound information. Embodiments of the present invention address some of the stated issues of the AMR based data/Ethernet design in a new and effective way.
The present invention employs features of the AC-97 specification to enable a novel data communication system. The Time Division Multiplexed (TDM) data frame employed in AC-97 protocol devices has time slots that are unused in the most common applications on PCs and workstations. Many of the time slots are allocated to audio communication which is usually done with separate sound cards on most modern systems. Telephone communication primarily uses the audio slots to communicate telephone data or voice to Coder Decoder (CODEC) devices. CODEC devices, in general, comprise devices that encode (analog to digital) analog (data, audio, video, etc) signals to digital and decode (digital to analog) digital data back to respective analog signals. The Tag time slot in the AC-97 data frame is useable to signal an AC-97 controller to use or ignore information in data frame slots. With the addition of some logic and control signals in an AC-97 data communication controller, embodiments of the present invention enable devices other than AC-97 to be coupled to the AC-97 protocol data link, and AC-97 protocol and non-AC-97 protocol communication may be done concurrently using the AC-97 protocol link. Ethernet, HPNA, Attachment Unit Interface (AUI) are some but not all of the protocols that are possible using embodiments of the present invention.
The foregoing has outlined the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.